The present invention relates to a capsule for storing and vibration mixing of two component materials for dental application, particularly of amalgam components.
A known capsule for separate storage and vibration mixing of amalgam components (U.S. Pat. No. 3,139,181) has a generally cylindrical lower capsule part containing the mixing space, and an upper part for storing the first component. The second component is disposed in the mixing space along with a pestle. Immediately before the mixing of the components the first component is introduced into the mixing space by a screwing movement exerted on the upper capsule part. Then the capsule is inserted in the vibration mixer which causes the capsule to move back and forth at a high frequency in the longitudinal direction, whereby the second component forms a homogeneous mixture with the first component. A disadvantage of this known multicomponent capsule is that a specific manipulatory movement must be executed before the mixing process in order to transfer the first component into the mixing space.
In another known arrangement (Ger. Pat. App. No. 28 31 005), one of the two components to be mixed is stored packaged in a foil or film bag in the mixing space, while the other component is stored open in the space. When the mixing vibration starts, it causes the foil or film bag to break, thus liberating the component stored therein to be mixed with the other component. This arrangement has the advantage that no specific manipulation is required to transfer the first component into the mixing space. However, there are problems associated with packaging the component in the foil or film bag. In particular, it is virtually impossible to weld-seal the bag so as to leave a consistent, small free volume above the component. This variation in free volume has a major effect on the time at which the bag breaks after the onset of the vibration action. Accordingly, it is difficult to achieve consistently good mixing given a prescribed mixing time. Also, there is the possibility that part of the broken bag will end up in the final amalgam and contaminate it.
A similar arrangement has been proposed (Ger. Pat. App. No. 30 25 526) in which the two components in the capsule are separated by a wall which divides the mixing space into two compartments and which has a bonding locus near its junction with the interior surface of the mixing space. The bonding locus is caused to break under the influence of the mixing vibration. The separating wall is preferably of a soft elastic material such as silicone rubber. However, this capsule also has the disadvantage that it is difficult to control sufficiently accurately the time at which the bonding locus of the separating wall will open or break.
The two last-mentioned capsules additionally have the disadvantage that a pestle cannot be used with them, and therefore the second component may be employed only in powder form and not in tablet form. In dental amalgams, where the first component is comprised of mercury and the second is comprised of a silver alloy, it is very advantageous for the latter to be employable in table form, to facilitate the control of the quantity employed.
Accordingly, it is an object of the present invention to devise a capsule for the storing and vibration mixing of dental two component materials, particularly of dental amalgam components, whereby the above-mentioned disadvantages of the known capsules can be avoided.
This object and other are achieved by a capsule for storing and vibration mixing of amalgam components or other two component materials for dental application according to the present invention. The capsule includes a mixing space which contains a first component and a pestle. The pestle is a hollow body containing a second component. The hollow body has a cover secured thereto and includes at least one opening for permitting the exit of the second component. The second component is rendered capable of passing through the opening by a mixing vibration movement of the body.
The inventive capsule has the advantages, first, that no special manipulation is required to transfer the one component into the mixing space prior to mixing the components, and secondly, a pestle is employed, thus permitting the other component to be used in tablet form. Since the mixing of the components is associated with substantial evolution of heat as a result of internal friction, a pestle with a metal cover may be used to facilitate heat removal. The metal cover also affords higher weight, which is beneficial for comminuting the tablets. The double containment within the pestle and the capsule provided for the mercury in the pestle is well suited for storing the mercury, and provides good oxidation protection. Further, in case of a defect in the seal of the pestle, the mercury is retained in the plastic capsule and cannot cause external pollution during shipping or storage.